CHEMICAL BONDING AND STRUCTURE Flashcards Preview

EDEXCEL Chemistry a level > CHEMICAL BONDING AND STRUCTURE > Flashcards

Flashcards in CHEMICAL BONDING AND STRUCTURE Deck (88)
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1

metallic bonding

strong electrostatic attraction between the nuclei of metal cations and delocalised electrons.

2

metals properties

high mp/bp
high thermal/electrical conductivity
malleable
sonorous
ductile
low IE's

3

Why do metals have high mp's?

Need to break strong forces of attraction between the cation nuclei and delocalised electrons.
also giant lattice structure requires much energy to break

4

What determines bp/mp's?

no. of delocalised electrons (group 1 is low while d-block metals are higher)
size of cation (smaller radii has closer electrons to nuclei higher mp)

5

electrical conductivity in metals

movement of delocalised electrons towards the positive terminal of a cell with a potential difference.

6

thermal conductivity

delocalised electrons passing KE along metal.

7

malleability

shape configuration

8

ductility

ability to draw metal into a wire

9

what does ductility and malleability depend on?

the cation and electron movement ability. layers slide over one another and delocalised electrons prevent strong forces of repulsion between cations.

10

ionic bonding

strong electrostatic attraction between oppositely charged ions.

11

arrangement of ionic substances

giant ionic lattice in which electrostatic attraction occurs in all directions.

12

how do you determine the strength of electrostatic attractions in an ionic substance?

calculation of energy per mole of solid needed to separate ions to infinity in which ions can no longer interact

13

how is strength of ionic bonding affected by size of cation?

as cation size increases, amount of energy needed to separate them decreases

14

how is strength of ionic bonding affected by size of anion?

increases as anion size increases

15

how does size of ions affect energy needed to separate ionic substances to infinity?

smaller substances require more energy to separate

16

why must data of ionic radii all come from the same source?

because radii is difficult to measure and several methods could conflict in accuracy.

17

properties of ionic substances

high mp/bp
brittle
water-soluble
poor electrical conductivity as a solid

18

why do ionic substances have high melting points?

giant lattice networks of oppositely charged ions have combined large electrostatic forces.

19

why are ionic substances brittle?

as stress causes ionic layers to slide over one another, meaning same charge ions are next to each other, repelling

20

why are ionic substances water soluble

polarity of water molecues allows separation of ions

21

reason for electrical conductivity when molten

previously fixed electrons become mobile, allowing a migration of electrons towards the positive terminal

22

what sort of current is used in electrolysis

direct

23

covalent bonding

2 atoms overlapping atomic orbitals of which contain a singular electron

24

3 ways covalent bonds interact

sigma (2 s orbitals)
sigma (2 P orbitals)
pi (2 P orbitals)

25

how may pi orbitals form? how does this affect the molecule?

sigma bonds may lead to the formation of pi bonds, creating larger electron density above and below the molecule

26

bond length

the distance between nuclei of 2 atoms covalently bonded.

27

how does bond length affect covalent bond strength

shorter length, greater strength

28

electronegativity

the ability of an atom to attract a bonding pair of electrons.

29

how does electronegativity change over the periodic table?

decreases down groups
increases across periods

30

What are polar molecule electron densities like?

they form asymmetrical electron densities, resulting in one atom having a slight positive charge and the other a slight negative charge (delta minus and delta plus)